Assessment of devolatilization schemes in predicting product yields of biomass fast pyrolysis

Abstract

Three devolatilization schemes to simulate biomass fast pyrolysis were tested and validated in this study. Fast pyrolysis is an attractive process in converting lignocellulosic biomass to valued products. Accurate numerical models can help understand the conversion process and be used for reactor design and optimization. This study used a numerical model that considered the multiphase hydrodynamics and chemical reactions of biomass fast pyrolysis. The gas and solid phases were simulated by using a multifluid model that considered multiple species in each phase. Three devolatilization schemes for biomass fast pyrolysis were incorporated into the model to simulate the tempo-spatial evolutions of all phases and species. The predicted product yields were compared and validated using experimental data. It was found that the best predictions were given by a scheme that used three components to represent biomass and also considered organic liquid cracking into gas. Under the reactor conditions studied, all three devolatilization schemes predicted relatively fast decomposition of biomass and the reactor hydrodynamics was not significantly affected by the specifics of the devolatilization schemes. Overall, an accurate devolatilization scheme to simulate the chemical changes of biomass particles is essential to predicting the product yield of biomass fast pyrolysis at the reactor scale.

Copyrolysis energy analysis of municipal solid waste and agricultural stalk

“…Maximum gas yields occurred with 6508C, and obtained as 14.36 wt % of MSW, 24.00 wt % of CAS, and 27.62 wt % of COS, respectively. This result was in agreement with previous studies [13,14], though the different samples and pyrolysis reactor systems were applied [15,16]. The reduction of char yields with increasing temperature could be attributed to the greater primary decomposition of the organic ingredients of MSW with agricultural stalk at higher temperature and/or secondary thermal decomposition of the char formed before being entrained out of the reaction zone.…”

Numerical simulation of biomass fast pyrolysis in an auger reactor

“…This reaction mechanism was chosen because it has been shown to be able to predict the biomass fast pyrolysis products when used in CFD simulations [38,43]. Note that comprehensive reaction kinetic schemes [44] can provide more detailed information, but their use in multi-dimensional CFD simulation may be computationally prohibitive.…”

“…On the basis of our previous studies [37][38][39], a multi-fluid model was used to simulate the hydrodynamics and heat transfer in the fast pyrolysis reactor. In a MFM, all phases are treated as interpenetrating continua, and the governing equations for mass, momentum, and energy conservations are solved to obtain the spatiotemporal evolutions of the phase volume fraction, velocity, temperature, and species mass fraction.…”

“…Because of the simple geometry, temperature control and operation of fluidized beds are more straightforward than for other types of reactors. Therefore, in the research discussed in this paper, we continued our previous studies [37][38][39] on CFD simulation of biomass fast pyrolysis in a bubbling fluidized-bed reactor and conducted further analyses of the simulation results to characterize the pyrolysis product yields.…”

Analytical Simulation of the Cloud Combustion of Corn Starch Microparticles

“…Today, computational methods receive a lot more attention from researchers than before. This is mainly due to the much lower costs and relatively acceptable results of these methods in comparison to experimental techniques in different aspects of mechanical engineering, such as enhanced oil recovery and new energies [1][2][3][4], biomass gasification [5][6][7][8][9][10][11][12] and pyrolysis [13][14][15][16][17][18][19][20][21][22], chemical reactions [23][24][25][26], molecular dynamics [27,28], smoothed particle hydrodynamics [29], and nanofluid applications [30][31][32]. An important aspect of mechanical engineering that needs to be investigated in detail is the combustion of solid particles.…”